[ros-diffs] [ilardig] 48383: [freeldr] - Patch by Carlo Bramini reviewed by lassy: The CF must be tested when reading time because the legacy DS12x87 chip shows a condition where it's updating its time registers and if it's the case then the call should be retried later. Now the time is valid when both CF flags for date and time are good at the same time. It's better to send the correct value of CF with the proper field to the REGS structure instead of hoping that the flag won't be changed by compiled code. In the Int386() function I did the fix for acquiring the status flags to send to the software interrupt. I also think it is also a good idea to always clear the direction flag before doing movsb/movsw/movsd in this function. Since we are working with DOS stuff, the state of the direction register could be unknown, who knows what happens after those INT opcodes. Afterall I don't think that adding these two "cld" would be a big problem. See issue #2786 for more details.

ilardig at svn.reactos.org ilardig at svn.reactos.org
Sat Jul 31 21:00:41 UTC 2010


Author: ilardig
Date: Sat Jul 31 21:00:40 2010
New Revision: 48383

URL: http://svn.reactos.org/svn/reactos?rev=48383&view=rev
Log:
[freeldr]
- Patch by Carlo Bramini reviewed by lassy:
The CF must be tested when reading time because the legacy DS12x87
chip shows a condition where it's updating its time registers and if it's the
case then the call should be retried later. Now the time is valid when both CF flags for date and time are good at the same time.
It's better to send the correct value of CF with the proper field to the REGS structure instead of hoping that the flag won't be changed by compiled code.
In the Int386() function I did the fix for acquiring the status flags to send to the software interrupt.
I also think it is also a good idea to always clear the direction flag before
doing movsb/movsw/movsd in this function. Since we are working with DOS stuff,
the state of the direction register could be unknown, who knows what happens
after those INT opcodes. Afterall I don't think that adding these two "cld"
would be a big problem.
See issue #2786 for more details.

Modified:
    trunk/reactos/boot/freeldr/freeldr/arch/i386/int386.S
    trunk/reactos/boot/freeldr/freeldr/arch/i386/pcrtc.c
    trunk/reactos/boot/freeldr/freeldr/include/arch.h

Modified: trunk/reactos/boot/freeldr/freeldr/arch/i386/int386.S
URL: http://svn.reactos.org/svn/reactos/trunk/reactos/boot/freeldr/freeldr/arch/i386/int386.S?rev=48383&r1=48382&r2=48383&view=diff
==============================================================================
--- trunk/reactos/boot/freeldr/freeldr/arch/i386/int386.S [iso-8859-1] (original)
+++ trunk/reactos/boot/freeldr/freeldr/arch/i386/int386.S [iso-8859-1] Sat Jul 31 21:00:40 2010
@@ -23,6 +23,10 @@
 #define ASM
 #include <arch.h>
 
+/* Only these flags are propagated into Int386() */
+#define FLAGS_PROP	(I386FLAG_CF | \
+                     I386FLAG_ZF | \
+                     I386FLAG_SF)
 
 Int386_REGS:
 
@@ -85,6 +89,7 @@
 	movl	$Int386_REGS,%edi
 	movl	Int386_regsin,%esi
 	movl	$0x24,%ecx
+	cld
 	rep
 	movsb
 
@@ -101,6 +106,16 @@
 	movw	%cs:Int386_gs,%ax
 	movw	%ax,%gs					/* GS register */
 
+	/* Prepare EFLAGS for recover */
+	pushf
+	movw	%cs:Int386_eflags, %ax
+	popw	%cx
+	andw	$FLAGS_PROP, %ax
+	andw	$~FLAGS_PROP, %cx
+	orw		%cx, %ax
+	pushw	%ax
+
+	/* Recover general purpose registers */
 	movl	%cs:Int386_eax,%eax		/* EAX register */
 	movl	%cs:Int386_ebx,%ebx		/* EBX register */
 	movl	%cs:Int386_ecx,%ecx		/* ECX register */
@@ -108,6 +123,9 @@
 
 	movl	%cs:Int386_esi,%esi		/* ESI register */
 	movl	%cs:Int386_edi,%edi		/* EDI register */
+
+	/* Recover previously prepared flags */
+	popf
 
 	/* Do not set the flags register */
 	/* only return its value in regsout */
@@ -149,6 +167,7 @@
 	movl	$Int386_REGS,%esi
 	movl	Int386_regsout,%edi
 	movl	$0x24,%ecx
+	cld
 	rep
 	movsb
 

Modified: trunk/reactos/boot/freeldr/freeldr/arch/i386/pcrtc.c
URL: http://svn.reactos.org/svn/reactos/trunk/reactos/boot/freeldr/freeldr/arch/i386/pcrtc.c?rev=48383&r1=48382&r2=48383&view=diff
==============================================================================
--- trunk/reactos/boot/freeldr/freeldr/arch/i386/pcrtc.c [iso-8859-1] (original)
+++ trunk/reactos/boot/freeldr/freeldr/arch/i386/pcrtc.c [iso-8859-1] Sat Jul 31 21:00:40 2010
@@ -27,56 +27,66 @@
     static TIMEINFO TimeInfo;
     REGS Regs;
 
-    /* Some BIOSes, such as the 1998/07/25 system ROM
-     * in the Compaq Deskpro EP/SB, leave CF unchanged
-     * if successful, so CF should be cleared before
-     * calling this function. */
-    __writeeflags(__readeflags() & ~EFLAGS_CF);
+    for (;;)
+    {
+        /* Some BIOSes, such as the 1998/07/25 system ROM
+         * in the Compaq Deskpro EP/SB, leave CF unchanged
+         * if successful, so CF should be cleared before
+         * calling this function. */
+        Regs.x.eflags = 0;
+//        __writeeflags(__readeflags() & ~EFLAGS_CF);
 
-    /* Int 1Ah AH=04h
-     * TIME - GET REAL-TIME CLOCK DATE (AT,XT286,PS)
-     *
-     * AH = 04h
-     * CF clear to avoid bug
-     * Return:
-     * CF clear if successful
-     * CH = century (BCD)
-     * CL = year (BCD)
-     * DH = month (BCD)
-     * DL = day (BCD)
-     * CF set on error
-     */
-    Regs.b.ah = 0x04;
-    Int386(0x1A, &Regs, &Regs);
+        /* Int 1Ah AH=04h
+         * TIME - GET REAL-TIME CLOCK DATE (AT,XT286,PS)
+         *
+         * AH = 04h
+         * CF clear to avoid bug
+         * Return:
+         * CF clear if successful
+         * CH = century (BCD)
+         * CL = year (BCD)
+         * DH = month (BCD)
+         * DL = day (BCD)
+         * CF set on error
+         */
+        Regs.b.ah = 0x04;
+        Int386(0x1A, &Regs, &Regs);
 
-    TimeInfo.Year = 100 * BCD_INT(Regs.b.ch) + BCD_INT(Regs.b.cl);
-    TimeInfo.Month = BCD_INT(Regs.b.dh);
-    TimeInfo.Day = BCD_INT(Regs.b.dl);
+        if (!INT386_SUCCESS(Regs)) continue;
 
-    /* Some BIOSes leave CF unchanged if successful,
-     * so CF should be cleared before calling this function. */
-    __writeeflags(__readeflags() & ~EFLAGS_CF);
+        TimeInfo.Year = 100 * BCD_INT(Regs.b.ch) + BCD_INT(Regs.b.cl);
+        TimeInfo.Month = BCD_INT(Regs.b.dh);
+        TimeInfo.Day = BCD_INT(Regs.b.dl);
 
-    /* Int 1Ah AH=02h
-     * TIME - GET REAL-TIME CLOCK TIME (AT,XT286,PS)
-     *
-     * AH = 02h
-     * CF clear to avoid bug
-     * Return:
-     * CF clear if successful
-     * CH = hour (BCD)
-     * CL = minutes (BCD)
-     * DH = seconds (BCD)
-     * DL = daylight savings flag (00h standard time, 01h daylight time)
-     * CF set on error (i.e. clock not running or in middle of update)
-     */
-    Regs.b.ah = 0x02;
-    Int386(0x1A, &Regs, &Regs);
+        /* Some BIOSes leave CF unchanged if successful,
+         * so CF should be cleared before calling this function. */
+        Regs.x.eflags = 0;
+//        __writeeflags(__readeflags() & ~EFLAGS_CF);
 
-    TimeInfo.Hour = BCD_INT(Regs.b.ch);
-    TimeInfo.Minute = BCD_INT(Regs.b.cl);
-    TimeInfo.Second = BCD_INT(Regs.b.dh);
+        /* Int 1Ah AH=02h
+         * TIME - GET REAL-TIME CLOCK TIME (AT,XT286,PS)
+         *
+         * AH = 02h
+         * CF clear to avoid bug
+         * Return:
+         * CF clear if successful
+         * CH = hour (BCD)
+         * CL = minutes (BCD)
+         * DH = seconds (BCD)
+         * DL = daylight savings flag (00h standard time, 01h daylight time)
+         * CF set on error (i.e. clock not running or in middle of update)
+         */
+        Regs.b.ah = 0x02;
+        Int386(0x1A, &Regs, &Regs);
 
+        if (!INT386_SUCCESS(Regs)) continue;
+
+        TimeInfo.Hour = BCD_INT(Regs.b.ch);
+        TimeInfo.Minute = BCD_INT(Regs.b.cl);
+        TimeInfo.Second = BCD_INT(Regs.b.dh);
+
+        break;
+    }
     return &TimeInfo;
 }
 

Modified: trunk/reactos/boot/freeldr/freeldr/include/arch.h
URL: http://svn.reactos.org/svn/reactos/trunk/reactos/boot/freeldr/freeldr/include/arch.h?rev=48383&r1=48382&r2=48383&view=diff
==============================================================================
--- trunk/reactos/boot/freeldr/freeldr/include/arch.h [iso-8859-1] (original)
+++ trunk/reactos/boot/freeldr/freeldr/include/arch.h [iso-8859-1] Sat Jul 31 21:00:40 2010
@@ -58,6 +58,19 @@
 #define EXTERN(x)	.global x; x:
 
 
+// Flag Masks
+#define I386FLAG_CF		0x0001		// Carry Flag
+#define I386FLAG_RESV1	0x0002		// Reserved - Must be 1
+#define I386FLAG_PF		0x0004		// Parity Flag
+#define I386FLAG_RESV2	0x0008		// Reserved - Must be 0
+#define I386FLAG_AF		0x0010		// Auxiliary Flag
+#define I386FLAG_RESV3	0x0020		// Reserved - Must be 0
+#define I386FLAG_ZF		0x0040		// Zero Flag
+#define I386FLAG_SF		0x0080		// Sign Flag
+#define I386FLAG_TF		0x0100		// Trap Flag (Single Step)
+#define I386FLAG_IF		0x0200		// Interrupt Flag
+#define I386FLAG_DF		0x0400		// Direction Flag
+#define I386FLAG_OF		0x0800		// Overflow Flag
 
 
 #ifndef ASM
@@ -148,20 +161,6 @@
 // specifically handles linear addresses.
 int		Int386(int ivec, REGS* in, REGS* out);
 
-// Flag Masks
-#define I386FLAG_CF		0x0001		// Carry Flag
-#define I386FLAG_RESV1	0x0002		// Reserved - Must be 1
-#define I386FLAG_PF		0x0004		// Parity Flag
-#define I386FLAG_RESV2	0x0008		// Reserved - Must be 0
-#define I386FLAG_AF		0x0010		// Auxiliary Flag
-#define I386FLAG_RESV3	0x0020		// Reserved - Must be 0
-#define I386FLAG_ZF		0x0040		// Zero Flag
-#define I386FLAG_SF		0x0080		// Sign Flag
-#define I386FLAG_TF		0x0100		// Trap Flag (Single Step)
-#define I386FLAG_IF		0x0200		// Interrupt Flag
-#define I386FLAG_DF		0x0400		// Direction Flag
-#define I386FLAG_OF		0x0800		// Overflow Flag
-
 // This macro tests the Carry Flag
 // If CF is set then the call failed (usually)
 #define INT386_SUCCESS(regs)	((regs.x.eflags & I386FLAG_CF) == 0)




More information about the Ros-diffs mailing list